Joint interpretation of geoelectrical and volatile organic compounds data: a case study in a hydrocarbons contaminated urban site

Abstract

As a result of a gasoline spill in an urban area, Electrical Resistivity Tomography (ERT), Electromagnetic Profiling (EMP) and Volatile Organic Compounds (VOC) methods were used in order to define the contamination plume and to optimize the drilling and soil sampling activities. The VOC anomalies (recent contamination) indicated that a gas station located at the study site is an active contamination source. The mature contaminated zones defined by ERT and EMP methods corresponded with low resistivity anomalies due to degradation process of the hydrocarbons contaminants. The ERT, EMP and VOC results were integrated on a map, allowing the final configuration of contamination plumes and the optimization of drilling and soil/freeproduct sampling. Laboratory analyses of free-product samples suggest the existence of more than one contamination event in the site, with the presence of recent and degraded-hydrocarbon contaminants classified in the gasoline range. This study shows the advantages of joint application of ERT, EMP and VOC methods in sites with active contamination source, where the existence of recent and mature contaminants in subsoil is assumed.

Comparative analyzes among electrical resistivity tomography arrays in the characterization of flow structure in free aquifer

“…The Dipole-dipole array of characterized by the increasing separation between electrodes or dipoles of current and potential (Mussetti & Khan, 2000). Several papers describe its applicability in the study of organic and inorganic contaminations in saturated zone conditions, proved by chemical analysis (Moreira et al 2006;Arango-Galván et al, 2011;Belmonte-Jiménez et al, 2012;Delgado-Rodríguez et al, 2014).…”

Análise comparativa entre arranjos de tomografia elétrica no reconhecimento de estruturas de fluxo em aquífero fraturado em Caçapava do Sul (RS)

“…O arranjo dipolo-dipolo é caracterizado pela separação crescente entre eletrodos ou dipolos de corrente e potencial, ou seja, quanto maior a distância entre dipolos, maior a profundidade de investigação e menor será a intensidade de campo potencial para o caso de intensidade de corrente elétrica fixa (Mussett & Khan, 2000). Diversos trabalhos demostram sua aplicabilidade no estudo de contaminações orgânicas e inorgânicas em condições de zona saturada, comprovadas por análises químicas (Moreira et al, 2006;Arango-Galván et al, 2011;Belmonte-Jiménez et al, 2012;Delgado-Rodríguez et al, 2014).…”

Characterization of Hydrocarbon-Contaminated Sites Based on Geoelectrical Methods of Geophysical Exploration

“…Several investigations have demonstrated the successful application of the surface resistivity methods for configuration (in plan and depth) of the hydrocarbon-contaminated zones. Electrical resistivity tomography (ERT) and electromagnetic profiling (EMP) methods are useful for the delimitation of the resistivity anomalies caused by different types of hydrocarbon contaminants and rocks in rural [4,5], industrial [6], and urban [7] sites. Soil resistivity depends mainly on water content and its salinity, clay content, and porosity.…”